Spectroscopic and Electrical Insights into Humidity-Induced Modifications of Graphene Structures

This paper explores the environmental sensitivity of monolayer graphene-based sensor devices for use as sensors under controlled humidity conditions using a combination of scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Kelvin probe force microscopy (KPFM). The structural and electrical responses of the graphene devices were examined before and after exposure to water vapor. Raman spectroscopy confirmed the presence of minor defects localized near the contacts, while FTIR revealed distinct spectral changes associated with the adsorption of H₂O and displacement of preadsorbed CO₂. KPFM mapping demonstrated surface potential redistribution and a reduction of the work function, consistent with improved carrier mobility upon water adsorption. Electrical measurements showed resistance variations that diverge from theoretical predictions for pristine graphene, indicating that environmental contaminants strongly influence device behavior. These results highlight the dual role of water as both a contaminant stabilizer and a charge redistribution agent, emphasizing the importance of environmental control for graphene-based sensing applications, or the inclusion of the expectations of the shift of electric properties caused by the environmental contaminants.